Process of liquidation of natural silk threads



Patented Ma 21, 1929.

UNITED. STATES PATENT OFFICE.

'romosuxn MUTO AND sABuno HIDA, OF'KOBE,IJ IAIPAN, assrenons 'ro KANEGA-room nosnxr KABUSHIKI KWAISHA, or TOKYO-EU, JAPAN.

PROCESS OF LIQUIDATION OF NATURAL SILK THREADS.

1T0 Drawing. Application filed February 21, 1928, Serial No. 256,059,and in Japan December 15, 1927.

This invention relates to improvements in the process of dissolvingnatural silk threads and is characterized by the fact that the naturalsilk is colloidally dissolved in a solution by treating the silk with asolution of magnesium nitrate or other soluble magnesium salts, and thenremoving the magnesium salts from the solution.

The main object of this invention is to prepare a colloidal adhesiveliquid of natural silk from natural raw silk threads, silk yarn, silkwaste, old silk cloth or other. similar raw silk materials by a simpleandeconomical process, to regenerate silk threads from the liquid or tobe utilized in manufacture of plastic materials or painting materialsetc.

Heretofore there has been little success in attempts to re-gain silkthreads, artificially from liquefied silk, which have high strength andtenacity because threads heretofore formed from solutions of liquefiedsilk have been brittle.

According to the present invention, these defects are overcome and weare able toobtain threads from a silk solution which possess goodstrength and tenacity characteris- .By way of example of carrying outour invention in practice we proceed as follows. About ten parts ofmagnesium nitrate are dissolved in five parts of water and this solutionis heated to a temperature of about 110 (3., then two or three parts ofwaste silk threads divided in several small quantities are successivelyadded, dipped into the said magnesium nitrate solution and stirredgently a-nd dissolved to form a suspending colloidal solution. Afterthat the magnesium salt added is separated and expelled from thissuspending solution by dialysis or other ordinary separating method.Dialysis is the preferred method and is accomplished by simply placingthe solution in an unglazed earthenware pot surrounded by pure water.Under such conditions, the magnesium nitrate passes through the pot intothe water whereas the colloidal silk remains behind. The method ofseparation by dialysis is a well known colloidal chemical process andneeds no further description. The suspension of natural silk thus formedis new concentrated at a comparatively low'temperathen drawn intocoagulating solution bath such as acetic acid, methyl-alcohol or otherknown dehydrating agents. In other cases we may prepare thin paperlikesheets of natural silk by spreading the said concentrated liquid silkover a flatsurface such as glass plate and drying the film. A suitablequantity of gelatin, glucose etc. may be added either before or afterthe expelling of salts to modify the strength and elasticity of thefinished thread.

As is shown in the aforesaid explanation one of the characteristics ofthis invention resides in the use of magnesium nitrate or other solublemagnesium salts as liquefying agents for the natural silk threads. Owingto this reason it is easy to remove the magnesium salts from thecolloidal solution of the natural .silk and recover a good producthaving devention as claimed, and, accordingly we beg to intend not to belimited as to the details described.

We claim The method of preparing a'colloidal solution of natural silkwhich comprises dissolving the silk in a solution of magnesium nitrateand then subjecting the solution to dialysis to free it of the magnesiumnitrate.

In.testimony whereof we have affixed our signatures.

'IOMENGSUKE MUTO. SABURO HIDA.

